Chapter 11: Chemical Reactions Notes-Part 1
Section 11.1 – Describing Chemical Reactions
In a chemical reaction, the reactants are written on the
left and the products on the right. The arrow that
separates them is called yield.
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Word Equations
To write a word equation, write the names of the
reactants and products in a sentence form.
Ex: chemical equation
2H2(g) + O2(g) → 2H2O(l)
Ex: word equation
Hydrogen gas and oxygen gas react to form liquid
water.
Symbol
Meaning
yields
Reversible reaction
Sample Problem #1
Write a sentence that describes this chemical reaction:
Na(s) + H2O(l) → NaOH(aq) + H2(g)
Practice Problem #1
Write a sentence that describes this reaction:
H2SO4(aq) + BaCl2(aq) → BaSO4(s) + HCl(aq)
solid
liquid
gas
aqueous
catalyst
Sample Problem #2
Write the chemical equation for the following reaction:
Hydrochloric acid and solid sodium hydrogen carbonate react
to produce aqueous sodium chloride, water, and carbon
dioxide.
heat
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A catalyst is a substance that speeds up a reaction but is
not used up in the reaction.
Practice Problem #2
Write the chemical equation for the following reaction:
Solid iron(III)hydroxide is heated to form solid iron(III)oxide and
Chapter 11: Chemical Reactions Notes-Part 1
water
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Make sure to reduce the coefficients to the lowest
whole-number ratio.
Balancing Chemical Equations
Coefficients are the numbers in front of a chemical formula.
Subscripts are numbers that show the number of atoms in a
compound.
When balancing reactions, you can only change the
coefficients, not the subscripts.
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A coefficient of one is understood and does not need to
be written.
Sample Problems
Balance the following equations:
1.
___H2 + ___O2 → ___H2O
2.
___AgNO3 + ___H2S → ___Ag2S + ___HNO3
3.
___Zn(OH)2 + ___H3PO4 → ___Zn3(PO4)2 + ___H2O
Practice Problems
1.
___FeCl3 + ___NaOH → ___Fe(OH)3 + ___NaCl
A skeleton equation is an equation that has no coefficients.
2.
___CS2 + ___Cl2 → ___CCl4 + ___S2Cl2
To balance a chemical equation, you add coefficients to the
substances so that the reactant and product side of the
equation contain equal numbers and types of atoms.
3.
___C2H6 + ___O2 → ___CO2 + ___H2O
Coefficients are added so that the equation follows the law of
conservation of mass.
Section 11.2 – Types of Chemical Reactions
The five general types of reactions are synthesis,
decomposition, single displacement, double displacement,
and combustion.
Synthesis Reactions
Rules for Balancing Equations
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Balance hydrogen and oxygen last.
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Count a polyatomic ion as a single unit if it appears
unchanged on both sides of the equation.
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If you end up with an odd number, you can double all of
the coefficients.
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In a synthesis reaction, two or more substances react to
form one product.
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Generic Reaction:
A + B → AB
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Actual Example: 2Mg + O2 → 2MgO
Chapter 11: Chemical Reactions Notes-Part 1
Predicting Products
1.
Cu + S →
2.
Be + O2 →
3.
Fe + S →
Solubility Rules Table
(Hint: copper is +1)
(Hint: iron is +3)
Decomposition Reactions
A decomposition reaction occurs when a single reactant
breaks down into two or more products.
Generic Reaction: AB → A + B
Actual Example: 2HgO → 2Hg + O2
Predicting Products
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Predict the products for the following reactions:
1.
H2O →
2.
HI →
3.
NH3 →
Predicting Precipitates
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You can predict whether a precipitate forms by using
solubility rules. (refer to solubility chart)
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If a substance is soluble, then it will dissolve in water and
be aqueous.
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If a substance is insoluble, then it will bond with another
ion and will be a solid.
Rules for Predicting Precipitates
Switch the ions and balance the charges to form the products.
Balance the equation.
Identify whether the products are solid or aqueous.
Chapter 11: Chemical Reactions Notes-Part 1
Sample Problem
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Double Displacement Reactions (refer to solubility rules)
Predict the products for the following reaction: HCl(aq) +
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AgNO3(aq) →
of two positive ions between two compounds.
Practice Problems
1. Predict the products for the following reaction:
Pb(C2H3O2)2(aq) + LiCl(aq) →
2. Predict the products for the following reaction: NH4Cl(aq) +
Ba(NO3)2(aq) →
Single Displacement Reactions (refer to solubility rules)
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A double displacement reaction involves the exchange
A single displacement reaction occurs when one
element replaces a second element in a compound.
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Generic Reaction: A + BC → B + AC
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Actual Example: Zn + Cu(NO3)2 → Cu + Zn(NO3)2
Predicting Products
Predict the products for the following reactions:
Br2 + NaI →
Fe + Pb(NO3)2 →
(Hint: iron is +3)
Zn + H2SO4 →
(Hint: zinc is +2)
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Generic Reaction: AB + CD → AD + CB
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Actual Example: 2NaCN + H2SO4 → 2HCN + Na2SO4
Predicting Products
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Predict the products for the following reactions:
1.
CaBr2 + AgNO3 →
2.
FeS + HCl →
3.
NaOH + Fe(NO3)3 →
Combustion Reactions
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A combustion reaction occurs when a substance burns in
oxygen and produces a lot of heat and light.
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Generic Reaction: CxHy + O2 → CO2 + H2O
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Actual Example: 2C8H18 + 25O2 → 16CO2 + 18H2O
Predicting Products
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Predict the products for the following reactions:
1.
C6H6 + O2 →
2.
C7H16 + O2 →
3.
C6H12O6 + O2 →